To compare blood glucose control when using insulin glargine twice daily at breakfast- and dinner-times with insulin glargine once daily at dinner time, in unselected people with Type 1 diabetes using insulin aspart at meal-times.Methods
In this 8-week, two-way, cross-over study, 20 people with Type 1 diabetes were randomized to insulin glargine injection once daily at dinner-time or twice daily at breakfast- and dinner-times, both plus meal-time insulin aspart. Each 4-week treatment period concluded with a 24-h inpatient metabolic profile.Results
Insulin doses, HbA1c, fructosamine concentration and pre-breakfast self-monitored blood glucose (SMBG) concentration did not differ between treatment periods. SMBG concentrations after breakfast, after lunch and before dinner were lower with twice-daily compared with once-daily dinner-time glargine [9.3 ± 0.5 (± SE) vs. 6.7 ± 0.5 mmol/l, P = 0.003; 10.2 ± 0.9 vs. 7.0 ± 0.9 mmol/l, P = 0.024; 9.6 ± 0.5 vs. 6.6 ± 0.5 mmol/l, P = 0.001]. Mean 24-h SMBG concentration was lower with twice-daily glargine (7.1 ± 0.5 vs. 8.8 ± 0.5 mmol/l, P = 0.031). Within-day variability of SMBG concentration was lower with twice-daily glargine (SD 3.2 ± 0.2 vs. 4.0 ± 0.3 mmol/l, P = 0.044). Plasma free insulin concentration was higher in the afternoon with twice-daily glargine (21.9 ± 1.4 vs. 16.1 ± 1.3 mU/l, P = 0.009), but lower overnight (12.1 ± 1.7 vs. 17.8 ± 1.7 mU/l, P = 0.030), compared with once-daily injection. Plasma glucose concentration overnight was higher with twice-daily compared with once-daily glargine (mean 9.0 ± 0.4 vs. 6.6 ± 0.4 mmol/l, P = 0.001).Conclusions
Blood glucose concentration rises in the late afternoon in association with falling plasma insulin levels towards the end of the 24-h period after insulin glargine injection in some people with Type 1 diabetes using once-daily glargine at dinner-time plus a rapid-acting insulin analogue at meal-times. This is prevented by twice-daily injection of insulin glargine.